Medical health organizations recommend increasing consumption of fish high in Omega-3 fatty acids to prevent cardiovascular disease, improve blood vessel health, and decrease whole-body inflammation. Unfortunately, large fish such as tuna, shark, swordfish, and king mackerel, often have unacceptably high levels of mercury that can cause serious health problems and birth defects.
A University of Quebec study of Nunavik Inuits living in northern Canada found that increased mercury levels were related to elevated systolic and diastolic blood pressures. Fish is the principle protein source of Nunavik Inuits. People, particularly pregnant or nursing women, should avoid fish high in mercury. Instead, they should eat fish lower in mercury, such as salmon, or take high-quality, uncontaminated fish oil supplements (300 mgs DHA per day) to get the benefits of Omega-3 fatty acids without the risks posed by high fish consumption. (Hypertension, 54: 981-986, 2009)